Since on Xbox we don't have BIOS interrupts, we have to implement all Disk I/O functions manually by talking to the Xbox IDE controller directly.
Xbox have just one IDE controller with primary HDD and slave DVD.
FreeLoader is missing support for ATAPI DVD-ROM drive which Xbox have. It could not read from it, so it does not allow to test bootcd or livecd ReactOS images.
See this portion of code:
Debug log and screenshot of XQEMU attached.